Field
Aspects of the present invention generally relate to a container included in an image forming apparatus and in which post-transfer residual toner is collected.
Description of the Related Art
In related-art electrophotographic image forming apparatuses such as printers, copiers, and facsimiles, some of the toner composing toner images formed on image bearing members, such as photoconductor drums and transfer belts, may be left on the image bearing members without being transferred to recording materials, such as paper. Such post-transfer residual toner left on the photoconductor drums and the transfer belts is removed therefrom by cleaning mechanisms and is conveyed by a toner conveying mechanism to a toner collecting case (a container) provided in the body of the image forming apparatus.
Typically, for example, such a toner collecting case is detachably attached to the body of the image forming apparatus. When the toner collecting case fills up with collected toner, the toner collecting case is detached from the image forming apparatus body and is replaced with a new toner collecting case. Currently, detecting that the toner collecting case has filled up occurs using, for example, a transparent or translucent detecting portion and an optical sensor. The detecting portion is provided at a part of the toner collecting case. The optical sensor includes a light-emitting portion and a light-receiving portion between which the detecting portion is positioned.
In such a case, when some toner is collected in the detecting portion and light emitted from the light-emitting portion is blocked by the collected toner before reaching the light-receiving portion, the toner collecting case is regarded as being full. In another case, the toner collecting case is held by an elastic member so that the toner collecting case is lowered in accordance with the weight of collected toner, and the lowering of the toner collecting case is detected by a sensor.
In the above two cases, only a single state of the toner collecting case is detectable. Therefore, to give the user time to prepare a new toner collecting case, an alert is issued when a nearly full state of the toner collecting case is detected. Thereafter, an estimation of when the toner collecting case will become full is made from the number of printed pages, and the image forming apparatus is stopped based on the estimation. However, the degree of difference between the estimation and the actual value varies with the degree of difference in the rate of printing area. Hence, the alert notifying the user of the nearly full state of the toner collecting case needs to be provided early enough to give the user enough time to prepare a new toner collecting case. Consequently, the image forming apparatus is occasionally stopped in spite of the toner collecting case still having enough room, which leads to unnecessary replacement of the toner collecting case.
To avoid the above issue, an apparatus is disclosed by Japanese Patent Laid-Open No. 2009-251088 in which the amount of toner is detected at different stages using a plurality of sensors.
According to Japanese Patent Laid-Open No. 2009-251088, however, providing a plurality of sensors can increase the manufacturing cost of the image forming apparatus. Furthermore, considering the configuration of the image forming apparatus, a satisfactorily long space is needed for the vertical movement of the toner collecting case, which can lead to an increase in the size of the image forming apparatus body.